This invention concerns a propulsion motor angle gearbox device housing for floating or submersible craft, more particularly motors mounted on boat or ship bows and poops.
More specifically, the invention concerns a housing or box designed to protect an angle gearbox of the type comprising:
two shafts rotating respectively with respect to two perpendicular rotating shafts, of which a first shaft is driven in rotation by a motor and a second shaft drives at least one propeller in rotation;
as well as mechanical parts such as gears comprising toothed gears and ball-bearings for transmitting rotation from said first shaft to said second shaft.
This type of device is used more particularly in retracing or tilting propulsion devices for use on floating units, in particular for leisure activities in which the propulsion device must be installed well forward in the hull of the boat. In patent WO 97/20733, propulsion units of this type are described, in particular lateral or longitudinal propulsion motors in which the propulsion motor is associated with a guiding arm, the upper part of which includes a motor, while the guiding arm encloses a rotating shaft connected to the motor and driving, at the other end, an angle gearbox device to ensure rotation of the shaft on which a propeller is mounted.
In prior embodiments of the angle gearbox device housing in the maritime area, or in other industrial areas, they are always made of a metallic material with a main part protecting the angle gearbox device comprising a single hollow casting within which are inserted blind aid shafts and said mechanical devices ensuring the angle drive to ensure protection that offers sufficient mechanical strength to take up the considerable forces of mechanical stress induced by the thrust of the shaft supporting said propulsion propeller and to which the housing is exposed when the angle gearbox device is in action. In the case of an immersed device, manufacturers generally use heavy and costly materials such as bronze for the additional requirements of resistance to corrosion.
In addition, this hollow protection metal casting requires precision machining that is lengthy and difficult to obtain.
Finally, because of its structure in a single hollow part of cast metal, the assembly of the various mechanical parts of the angle gearbox device in the housing is lengthy and difficult because it is carried out blind. The fitting of the complete device, in particular to ensure total perpendicularity of the rotating shaft axes in said part is difficult and cannot be inspected when the angle gearbox device is assembled inside the housing. In addition, it is necessary to carry out the full assembly of the angle gearbox device in the housing and assemble the housing with the other mechanical parts assembled at the output of the housing in line with the two shafts to make sure that the angle gearbox device is properly fitted in the housing and verify its alignment according to the adjustment tolerances of the various other components at the output of the housing in line with the two shafts.
These difficulties of alignment and adjustment are all the more evident in that the hollow metal casting is difficult to reproduce uniformly in production because of the amount of precision machining involved in its manufacture.
In addition, the housing consists of an assembly with three other fitted metal parts which must also be machined accurately. These fitted parts ensure the closing of the orifices in said main hollow part through which the various main mechanical components of the angle gearbox device are inserted into said main hollow part. The fitted parts cosign the insertion orifices of the angle gearbox device in said housing are attached to said main metal hollow casting according to a junction plane perpendicular to the rotating axes and, more particularly perpendicular to the propulsion shaft supporting the propeller. Thus, the thrust forces of the shaft supporting the propeller must be taken up by the means of attaching the fitted parts to said main hollow casting at the output orifice of the propulsion shaft supporting the propeller.
In all, because of the structure of the housings in prior embodiments, the machining and assembly of said housings and component parts are particularly lengthy and costly.
Accordingly, in side or longitudinal propulsion motors of the type described in Wo 97/20733, the cost of the housing and the assembly of the mechanical parts of the angle gearbox device it contains represent approximately two-thirds of the cost of the propeller motor.
In U.S. Pat. No. 3,946,698 and FR 2 517 018, there are known angle gearbox housings constructed from two half-shells of metallic alloy. In FR 2 517 018, the housing is no longer designed to be immersed in a marine environment for the propulsion of a propeller motor on a floating or submersible craft. In U.S. Pat. No. 3,946,698, the housing comprises two superimposed parts enclosing two angle gearbox devices in such a way that the rotating shaft connected to the motor is parallel to the rotating shaft connected to the propeller.
The problem of this invention is therefore of obtaining an angle gearbox drive device and ball-bearing housing for a floating or submersible craft propulsion motor wherein said angle gearbox device includes a rotating shaft connected to the motor and a perpendicular shaft connected to the propeller, and said housing sufficient mechanical strength to take up the mechanical thrust stresses transmitted by said device and taken up by the housing while overcoming the drawbacks of assembly and cost of prior metallic housings constructed of machined metal parts as described previously.
Another problem is of supplying a housing for use in a marine environment offering mechanical and watertightness stability properties, but also of hydraulic capability, in particular with a small volume and overall size, suitable for the conditions of use in immersion at a depth of at least 1 meter, and preferably at least 3 meters, with tightness designed more specifically to provide protection against the extended effects of immersion under pressure.
The research of the inventor in choosing the structure of the parts that may form the housing main protection body have resulted obtaining a solution to the problems raised with a housing whose main receptacle body for the angle gearbox device comprises several parts of a reinforced synthetic material cooperating to an appropriate junction plane.
More specifically, this invention supplies a propulsion motor angle gearbox device housing for boats intended to be immersed and to contain an angle gearbox device comprising:
two shafts rotating with respect to two perpendicular shafts, the first of which is driven in rotation by said motor, and a second shaft driving at least one propeller in rotation;
as well as the mechanical parts comprising the gears and ball-bearings for transmitting the rotation of said first shaft to said second shaft, characterized in that it comprises two assembled complementary half-shells made of a reinforced thermoplastic polymer synthetic material cooperating with one another according to a junction plane defined by said axes of rotation of said rotating shafts, and each offering in said junction plane:
a hollow area forming a receptacle for said angle gearbox device, and
a plane bearing surface outside said hollow area and serving as a support on the complementary shell.
Preferably, the two half-shells comprise, at their ends, half-sleeves in such a way that once the half-shells are assembled, they define a housing comprising;
an upper tubular sleeve through which said first shaft protrudes, and
at least one side tubular sleeve comprising at least one internal annular opening designed to receive said bearings, through which side sleeve a said second shaft penetrates,
and stable and sealed means of assembly of the two half-shells including tubular-shaped collars fitted around said tubular sleeves, which collars are preferably made of stainless steel.
Said collars provide a stable and sealed mechanical link between the two half-shells in a particularly advantageous manner because they cover the areas of the housing containing the bearings and/or that cooperate with the propellers, or an opening in a support element ensuring an interconnecting interface between the housing and the motor, and therefore exposed to considerable mechanical forces liable to cause mechanical breakage and/or tightness faults. Said collars, in particular, dispense with recourse to having on the surface of said sleeves, bosses through which holes are provided to permit an attachment of two half-shells by threaded device. Said bosses would be disadvantageous from the hydraulic and hydrodynamic standpoints regarding the outside profile of the housing, and would tend to increase the volume of said housing, which it is desirable to avoid in the immersed medium.
In addition, because at least one of the said sleeves is housed with a propeller hub, these bosses would mean forming an excessively large hollow in the propeller hub, reducing the mechanical strength of the propeller. Similarly, because the upper sleeve passes through an opening in said support element ensuring a link interface with the motor, a boss on said upper sleeve would mean creating a larger opening in said support element, which could cause mechanical fragility in the link between the upper sleeve and said supporting element. The tubular shape of the sleeves and columns would be an advantage for their incorporation in said cylindrical orifices through said support element and, respectively, the hub of said propeller, providing the best link between the housing and said supporting element and said propeller, whether with respect to mechanical or tightness aspects.
The combination, on the one hand, of the shape of the two half-shells which an be more or less symmetrical because they are assembled on a connecting plane comprising the axes of the two rotating shafts, and may even be absolutely identical, and on the other the material used, contribute to the mass production of a product offering high technical performance and easy assembly implementation under particularly advantageous economic conditions.
By virtue of the structure of the housing, in particular by the fact that the junction of the two half-shells and the closing of the housing are along a plane containing the two axes of rotation of the two shafts, it is possible, on the one hand, to install the complete angle gearbox device in the said hollow zone of one of said half-shells. Therefore, it is possible to check the fitting of the various mechanical components of the angle gearbox device before the assembly of the two half-shells and the closing of the housing. Further, the thrust forces along the longitudinal direction of said axes of rotation of said shafts are spread out and transmitted identically to the two shells and are not taken up exclusive by the attaching means of the two half-shells with one another, but are taken up essentially in the mass of the two shells. More particularly, the choice of a reinforced thermoplastic polymer synthetic material, both injectable through its thermoplastic properties and having properties of high mechanical strength because of its composite nature and the presence of reinforcements, such as mineral or synthetic fillers, makes it possible to obtain, by molding, high precision without the machining of the shells, offering high mechanical performance and perfect uniformity in production.
In a preferential embodiment, the housing according to the invention consists of two identical half-shells.
The identical structure of the two half-shells is an additional advantage because it allows the stocks to be rationalized and contributes to reducing costs in that there is only one part left to be injected. Further, there are no male shells or female shells, meaning that there are no possible errors.
It is advantageous if said bearing surface of each shell includes attaching openings permitting the mechanical assembly of the two half-shells by threaded devices such as screws, in an attaching zone located outside the end zones of said bearing surface forming said upper and side sleeves.
Again advantageously, said half-shells include, in said attaching zone of said bearing surface located below said upper sleeve, either side of the hollow zone receiving said first shaft, hollow cavities permitting the insertion of nuts attaching said housing to said support element to ensure an interconnection interface between the housing and the motor.
The tightness between the two half-shells can be obtained by spreading glue or sealing compound to said bearing surfaces or using an O-ring inserted into a seal groove.
In one advantageous embodiment, each half-shell includes a seal groove in said bearing surface between the receptacle hollow zone and an area comprising the means of attaching the shells together, said seal groove covering more than half the perimeter of the receptacle hollow zone so that said seals of the two shells overlap at an intersection point when the two shells are attached to one another. This overlapping of the seal guarantees complete tightness of the perimeter of the receptacle hollow zone to be protected.
Preferentially, each half-shell has an axis of symmetry corresponding to the axis of said rotating shafts when they are housed inside the receptacle hollow zone, and said seal groove follows the perimeter of one of the symmetrical halves of said shell while protruding from the axis of symmetry in order to open out at least on one end in a hollow part or outside said half-shell. This configuration will allow the creepage of the seal when compressed by junction and attachment of the two half-shells together.
In another alternative embodiment, the housing is constructed from two separate half-shells with, more particularly, a shell having a seal groove on the entirety of its perimeter and a half-shell without a seal groove.
To obtain high mechanical properties, the shells are made of a composite polymer reinforced by mineral or synthetic fillers, in particular in the form of fibers. In a preferred embodiment, the thermoplastic polymer material includes resistance to traction in excess of 200 MPa, preferably higher than 250 MPa and high rigidity with an elasticity modulus exceeding 10 GPa and preferably exceeding 15 GPa and a water absorption capacity of less than 0.5%, and preferably less than 0.15%
In particular, a high performance thermoplastic composite material based on polyphthalamides (PPA) is used, reinforced by glass fiber, preferably to approximately 40% by weight.
Therefore, the advantages of this invention are:
the properties of watertightness, hydraulic capability of the profile and mechanical strength of the housing, by the taking up of smaller stress forces at the attachment of the two shells and means of assembling the two half-shells comprising collars, and finally, the use of a reinforced thermoplastic polymer material,
advantageous conditions of production for injection molding by the absence of machining of parts and the total uniformity of the two half-shells, the ease of installation of the angle gearbox device in the housing, which is xe2x80x9copen skyxe2x80x9d, and the possibility of visually inspecting the fitting of said device in the housing and its alignment with respect to the other mechanical parts with which it cooperates outside the housing, in particular the fitting of the various gearwheels and bearings and the perpendicularity of the shafts in the receptacle hollow zone.
This generates a considerable reduction in manufacturing costs, capable of representing up to 30% compared to the total manufacturing cost of a propulsion motor.
a reduction in the weight of the housing by a factor of 4 to 5 and, thereby, a reduction in the propulsion motor of approximately 20%;
the absence of galvanic couple in the marine environment, which is one of the drawbacks in using metallic parts,
and finally, better resistance to corrosion than metallic parts.